nohz: Remove tick_nohz_idle_enter_norcu() / tick_nohz_idle_exit_norcu()

Those two APIs were provided to optimize the calls of
tick_nohz_idle_enter() and rcu_idle_enter() into a single
irq disabled section. This way no interrupt happening in-between would
needlessly process any RCU job.

Now we are talking about an optimization for which benefits
have yet to be measured. Let's start simple and completely decouple
idle rcu and dyntick idle logics to simplify.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

15 files changed, 67 insertions, 38 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 47e34c09127..e8e8fe505df 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -183,7 +183,8 @@ void cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		leds_event(led_idle_start);
 		while (!need_resched()) {
 #ifdef CONFIG_HOTPLUG_CPU
@@ -213,7 +214,8 @@ void cpu_idle(void)
 			}
 		}
 		leds_event(led_idle_end);
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c
index 34c8c703bb1..ea339575032 100644
--- a/arch/avr32/kernel/process.c
+++ b/arch/avr32/kernel/process.c
@@ -34,10 +34,12 @@ void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched())
 			cpu_idle_sleep();
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index 57e07498a0e..8dd0416673c 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -88,10 +88,12 @@ void cpu_idle(void)
 #endif
 		if (!idle)
 			idle = default_idle;
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched())
 			idle();
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 13d59f34b94..7dcb5bfffb7 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -103,10 +103,12 @@ void cpu_idle(void)
 		if (!idle)
 			idle = default_idle;
 
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched())
 			idle();
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 
 		preempt_enable_no_resched();
 		schedule();
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 17fb3a27016..7955409051c 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -56,7 +56,8 @@ void __noreturn cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched() && cpu_online(cpu)) {
 #ifdef CONFIG_MIPS_MT_SMTC
 			extern void smtc_idle_loop_hook(void);
@@ -77,7 +78,8 @@ void __noreturn cpu_idle(void)
 		     system_state == SYSTEM_BOOTING))
 			play_dead();
 #endif
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/openrisc/kernel/idle.c b/arch/openrisc/kernel/idle.c
index 2e82cd0fa5e..e5fc7887783 100644
--- a/arch/openrisc/kernel/idle.c
+++ b/arch/openrisc/kernel/idle.c
@@ -51,7 +51,8 @@ void cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 
 		while (!need_resched()) {
 			check_pgt_cache();
@@ -69,7 +70,8 @@ void cpu_idle(void)
 			set_thread_flag(TIF_POLLING_NRFLAG);
 		}
 
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 3cd73d1fc42..9c3cd490b1b 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -62,10 +62,10 @@ void cpu_idle(void)
 
 	set_thread_flag(TIF_POLLING_NRFLAG);
 	while (1) {
-		if (idle_uses_rcu)
-			tick_nohz_idle_enter();
-		else
-			tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		if (!idle_uses_rcu)
+			rcu_idle_enter();
+
 		while (!need_resched() && !cpu_should_die()) {
 			ppc64_runlatch_off();
 
@@ -102,10 +102,9 @@ void cpu_idle(void)
 
 		HMT_medium();
 		ppc64_runlatch_on();
-		if (idle_uses_rcu)
-			tick_nohz_idle_exit();
-		else
-			tick_nohz_idle_exit_norcu();
+		if (!idle_uses_rcu)
+			rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		if (cpu_should_die())
 			cpu_die();
diff --git a/arch/powerpc/platforms/iseries/setup.c b/arch/powerpc/platforms/iseries/setup.c
index d69d3d185e8..8fc62586a97 100644
--- a/arch/powerpc/platforms/iseries/setup.c
+++ b/arch/powerpc/platforms/iseries/setup.c
@@ -563,7 +563,8 @@ static void yield_shared_processor(void)
 static void iseries_shared_idle(void)
 {
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched() && !hvlpevent_is_pending()) {
 			local_irq_disable();
 			ppc64_runlatch_off();
@@ -577,7 +578,8 @@ static void iseries_shared_idle(void)
 		}
 
 		ppc64_runlatch_on();
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 
 		if (hvlpevent_is_pending())
 			process_iSeries_events();
@@ -593,7 +595,8 @@ static void iseries_dedicated_idle(void)
 	set_thread_flag(TIF_POLLING_NRFLAG);
 
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		if (!need_resched()) {
 			while (!need_resched()) {
 				ppc64_runlatch_off();
@@ -610,7 +613,8 @@ static void iseries_dedicated_idle(void)
 		}
 
 		ppc64_runlatch_on();
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 6fa987367ae..3201ae44799 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -91,10 +91,12 @@ static void default_idle(void)
 void cpu_idle(void)
 {
 	for (;;) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched())
 			default_idle();
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index ad58e7535a7..406508d4ce7 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -89,7 +89,8 @@ void cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 
 		while (!need_resched()) {
 			check_pgt_cache();
@@ -111,7 +112,8 @@ void cpu_idle(void)
 			start_critical_timings();
 		}
 
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 4a0e7d79cb9..39d8b05201a 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -95,12 +95,14 @@ void cpu_idle(void)
 	set_thread_flag(TIF_POLLING_NRFLAG);
 
 	while(1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 
 		while (!need_resched() && !cpu_is_offline(cpu))
 			sparc64_yield(cpu);
 
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 
 		preempt_enable_no_resched();
 
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index 53ac89595ab..4c1ac6e5347 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -85,7 +85,8 @@ void cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched()) {
 			if (cpu_is_offline(cpu))
 				BUG();  /* no HOTPLUG_CPU */
@@ -105,7 +106,8 @@ void cpu_idle(void)
 				local_irq_enable();
 			current_thread_info()->status |= TS_POLLING;
 		}
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 55d2cf455f6..69f24905abd 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -246,10 +246,12 @@ void default_idle(void)
 		if (need_resched())
 			schedule();
 
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		nsecs = disable_timer();
 		idle_sleep(nsecs);
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 	}
 }
 
diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index 095ff5a5792..52edc2b6287 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -55,7 +55,8 @@ void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched()) {
 			local_irq_disable();
 			stop_critical_timings();
@@ -63,7 +64,8 @@ void cpu_idle(void)
 			local_irq_enable();
 			start_critical_timings();
 		}
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index f94da3920c3..485204f58cd 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -99,7 +99,8 @@ void cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		tick_nohz_idle_enter_norcu();
+		tick_nohz_idle_enter();
+		rcu_idle_enter();
 		while (!need_resched()) {
 
 			check_pgt_cache();
@@ -116,7 +117,8 @@ void cpu_idle(void)
 				pm_idle();
 			start_critical_timings();
 		}
-		tick_nohz_idle_exit_norcu();
+		rcu_idle_exit();
+		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();